I take exception with that. Both Pleonast and I pointed out the international treaty, of which the United States is a signatory, that would require us to “inform the Secretary-General of the United Nations as well as the public and the international scientific community, to the greatest extent feasible and practicable, of the nature, conduct, locations and results of such activities.”
If they look like Daniela Hantuchova, I’m all for it. 
So we notify the Secretary-General, then what does he do after that? Do we treat the intelligent life with the same basic rights as we do here on Earth? Obviously we try to make contact with them, do we force ourselves on them? What if the ET’s want nothing to do with us (hypothetical)? Are we obligated to invade a planet?
I find it odd that audilover would say that “the fact is that we are not nearly as capable of pulling off gigantic conspiracies as the public would like to believe”, when there have been dozens, if not hundreds, of well documented conspiracies in the past 50 years, and any serious student of political knows that “the Big Lie” is not just a common (CYA is almost the instinctive first reaction in most large governments) but effective political technique.
Perhaps he merely meant to indicate that the public imagination exceeds the government’s capacity for conspiracy. However, this does not say anything about the government’s capacity to mold thought on the matter of life on Mars.
Anyone who followed the hard science of the Viking Life Detection Experiments knows that some came up positive, but the results were dismissed as “unknown soil chemstry”. Some experiments in the geophysical package also gave results that supported microbial life, but since they were not part of the biological package, they are only listed in more detailed analyses. What is less known is that almost 28 years later, no inorganic soil chemistry consistent with known Mars conditions and the Viking experiments has been proposed. Some possible categories of chemistry have been advanced (e.g. Fe(IV) and various forms of peroxides) but each example reaction presented does not fit the known Martian conditions, so the topic is still purely hypothetical: e.g. the Fe(IV) reaction presented by Tsapin et al (2000) requires strong alkaline conditions, while the Martian surface is, at best, mildly alkaline (see “Iron(VI) Seems an Unlikely Explanation for Viking Labeled Release Results” Icarus 159, 266-267 (2002) which contains a response by Tsapin; and extensive sensitive observations of Mars have ruled out the presence of peroxides.
Gerald V. Levin, an established scientist who heads the company [Biospherix] that built some of the Viking life detection experiments, has long reported that he was explicitly ordered not to report his findings as “positive” by a senior administrator who did not want to risk NASA looking foolish. He went along with serious misgivings, but especially since the NAtional Academy of Sciences 10th anniversary symposium on the landing, he has published many papers interpreting of the original results, and analyzing various soil chemistry and other abiogenic mechanisms that have been proposed. His conclusion has always been that the results are consistent with life, and that subsequent evidence has only strengthened the “case for life.”
He has long maintained that a certain culture among NASA employees, contractors, and allied institutions has created an institutional blindness to certain issues (which is partly why certain key observations that would support or disprove existing abiogenic explanations have not been made). This culture has been well documented in NASA, starting with the Challenger tragedy (which was coincidentally, also in 1986, the 10th anniversary of the Viking landing) and the more recent Columbia tragedy.
I am not saying that there has been a conspiracy, but there is simply no denying that NASA does not always react in the rational and open-minded manner we might ‘reasonably’ expect, when confronted with potentially embarassing or politically loaded information. I’ll concede that it often -even ‘usually’- reacts responsibly, but I would not consider it entirely reasonable to blithely expect it to do so. There are too many exceptions.
Why would life on Mars be embarrassing? Aside from the possibility of a public mistake, former NASA administrator Daniel Goldin and other official have noted concerns that such a discovery might upset the public e.g. on a Dec. 12, 1996, CNN Headline News story on NASA’S new “Origins” theme [following a NASA-sponsored meeting between scientists, theologians, Vice President Gore and NASA Administrator Goldin] Goldin commented on the possible religious backlash - whether or not life on Mars creates formal theological difficulties, the concern that many people might perceive it as posing difficulties was substantial. The publicity surrounding the "Mars meteorites’ may have been meant to ease into the topic, since it was inorganic evidence that life may have once existed in distant geological time.
Similarly, other sectors of society might have opinions which conflicted with NASA’s goals of exploration. Environmentalists might protest the possibility of contaminating a MArtian biosphere, if life on Mars were considered a probable fact. In the above telecast, and on countless other occcassions, Goldin has spoken about the precarious status of funding for various NASA projects, and the impact of public groups outside the space exploration sector, especially in the face of a generally tightening budget, shifting Congressional and Executive mandates, and operational setbacks.
An excellent technical bibliography of Dr. Levin’s peer-reviewed, published work can be found on the Biospherix website. The full text of each paper is available there.
I’m not shouting conspiracy, per se, but I think it is essential to read the actual science before debating this issue. I also think NASA’s culture and history (well known to most Americans today) supports the possibility that (as has so often happened in Western civilization) respected and knowledgeable bodies end up causing a delay of decades before the full appropriate impact of a groundbreaking finding. [e.g. the French Academy of Science rejected all evidence of meteorites out of hand in the 18th century ]
And you equate this to the OP’s contention that evidence of an abandoned outpost for some sort of intelligent life would be suppressed?